Mercurial > hg > truffle
diff src/share/vm/gc_implementation/g1/concurrentMark.cpp @ 1358:72f725c5a7be
6940310: G1: MT-unsafe calls to CM::region_stack_push() / CM::region_stack_pop()
Summary: Calling the methods region_stack_push() and region_stack_pop() concurrent is not MT-safe. The assumption is that we will only call region_stack_push() during a GC pause and region_stack_pop() during marking. Unfortunately, we also call region_stack_push() during marking which seems to be introducing subtle marking failures. This change introduces lock-based methods for pushing / popping to be called during marking.
Reviewed-by: iveresov, johnc
author | tonyp |
---|---|
date | Mon, 05 Apr 2010 12:19:22 -0400 |
parents | d4197f8d516a |
children | 23b1b27ac76c |
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--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp Fri Apr 02 12:10:08 2010 -0400 +++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp Mon Apr 05 12:19:22 2010 -0400 @@ -297,6 +297,11 @@ } } +// Currently we do not call this at all. Normally we would call it +// during the concurrent marking / remark phases but we now call +// the lock-based version instead. But we might want to resurrect this +// code in the future. So, we'll leave it here commented out. +#if 0 MemRegion CMRegionStack::pop() { while (true) { // Otherwise... @@ -321,6 +326,41 @@ // Otherwise, we need to try again. } } +#endif // 0 + +void CMRegionStack::push_with_lock(MemRegion mr) { + assert(mr.word_size() > 0, "Precondition"); + MutexLockerEx x(CMRegionStack_lock, Mutex::_no_safepoint_check_flag); + + if (isFull()) { + _overflow = true; + return; + } + + _base[_index] = mr; + _index += 1; +} + +MemRegion CMRegionStack::pop_with_lock() { + MutexLockerEx x(CMRegionStack_lock, Mutex::_no_safepoint_check_flag); + + while (true) { + if (_index == 0) { + return MemRegion(); + } + _index -= 1; + + MemRegion mr = _base[_index]; + if (mr.start() != NULL) { + assert(mr.end() != NULL, "invariant"); + assert(mr.word_size() > 0, "invariant"); + return mr; + } else { + // that entry was invalidated... let's skip it + assert(mr.end() == NULL, "invariant"); + } + } +} bool CMRegionStack::invalidate_entries_into_cset() { bool result = false; @@ -3363,7 +3403,7 @@ gclog_or_tty->print_cr("[%d] draining region stack, size = %d", _task_id, _cm->region_stack_size()); - MemRegion mr = _cm->region_stack_pop(); + MemRegion mr = _cm->region_stack_pop_with_lock(); // it returns MemRegion() if the pop fails statsOnly(if (mr.start() != NULL) ++_region_stack_pops ); @@ -3384,7 +3424,7 @@ if (has_aborted()) mr = MemRegion(); else { - mr = _cm->region_stack_pop(); + mr = _cm->region_stack_pop_with_lock(); // it returns MemRegion() if the pop fails statsOnly(if (mr.start() != NULL) ++_region_stack_pops ); } @@ -3417,7 +3457,7 @@ } // Now push the part of the region we didn't scan on the // region stack to make sure a task scans it later. - _cm->region_stack_push(newRegion); + _cm->region_stack_push_with_lock(newRegion); } // break from while mr = MemRegion();